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Full text of "Text Book Of Mechanical Engineering"

S6                                   Brazing.

in             proportions, the following percentages being-

:—

Copper   .          . .        ...        ...        •••      °       3

Tin         ...        .........        -.    84     9°

Antimony          ...        ..         ...        •••      8        7

TOO     IOO

of white metal for bearings is that it can be

run         the                     the journal is in place, and so ensure a-

fit.     It causes considerably less   friction  than brass or

To sum up then, alloys of copper and tin are termed bronzes,

and                a little zinc added up to about i \ or 3 per cent.

of           and 2inc are called brasses, Muntz metal being

one of          ; and those having tin and antimony, with a little

are          metals.

^   Brazing.—Brass or gun metal may be united by this process,
is also termed hard soldering;  and the joint will then
be as            as the original casting.

or steel  may  be also connected  by brazing if  more

especially finished pieces of work.    The method is to

first                clean the work with acid, then take some brass

mix with powdered borax as a flux, the borax being

moistened with water.*   The filings are placed between •

the           to be braced so as to form a joint, as much surface

for the latter as possible, and the two are held together

in             tongs, having thick jaws to keep the heat.    The tongs

will         the          and grip the pieces until perfectly set,- and the

be finished off in the vice.

If the work cannot be easily gripped, another way is to insert
the           as before, and, binding with iron wire, place the' pieces '

in a          coke fire until the operation is complete.

Or, still another method is to use the blow-pipe.    Here a fine
of very hot         is directed on to the work by blowing with' •
this instrument through a lighted 'Bunsen.'          *                 •   •

*            ge&omfy^ Instead of brass Slings, 'spelter* is used, which' is a

about equal parts of copper and zinc, and specially'

ft* bntafug pturposes*                        .                              ...   :-   '